Question

You and Mr. Fowles have decided to race each other at the Boston Marathon (26 miles long). Mr. Fowles runs at a steady 4.2 miles per hour. He knows your best time is 3 miles per hour so he gives you a 3 mile lead. When will he catch you? How far behind are you when Mr. Fowles finishes the race? How much longer will it take for you to finish?

Answer 1

The answer is below

Explanation:

Speed is the time rate of change of velocity, it is the ratio of distance to time.

Mr. Fowles runs at a steady 4.2 miles per hour. The time taken to cover 26 miles is:

speed = distance / time

time = distance / speed = 26 / 4.2 = 6.19 hour

I run at 3 miles per hour. I was given 3 mile lead, so the remaining distance is 23 miles (26 - 3). The time needed to complete the 23 miles is:

time = distance / speed = 23 / 3 = 7.67 hour

a) Let d be the distance Mr Fowles catches me. Hence:

time = (d + 3)/4.2; also time = d/3

(d + 3)/4.2 = d/3

3d + 9 = 4.2d

1.2d = 9

d = 7.5 miles

He would catch me at 10.5 (7.5 + 3) miles from the starting point.

b) Mr. fowles finishes after 6.19 hour. At that time, the distance is have covered is:

distance = 6.19 * 3 mi/hr = 18.57 mile

Distance behind = 23 mile - 18.57 = 4.43 mile

c) time longer = 7.67 hour - 6.19 hour = 1.48 hour